how is the lincoln power mig 255 working out?

[john walker's w]

i just bought one, and other than not working real well on 20ga sheetmetal, it seems heavy duty enough to last for years for everything else. anybody had any problems with them?

[Planet X]

Bought mine in Nov 00, and is working ok. How long have you had yours?
Are you interested in making welding on thin stuff easier?
What mix were you using?
What wire size & type?
What were your machine settings?
How about the weld direction and joint type and position?

Anwsers to the above questions would be a good starting point if you want to go there.

[john walker's w]

i've only had it a few days, so maybe some more time with it will produce better results on 20ga, but i'm not optimistic. it' just doesn't have a soft enough arc when turned down to the range that's suggested on the side panel for 20ga. (220 speed, 15V). i've adjusted it more and less, but still not happy. may have to get a 120V HH140 or something for the sheetmetal work. gas is C25, wire is .023, direction is right to left if that's what you mean, torch angled to the right a bit. for tack and spot 90°. butt welds on 20ga. i like to place a nice flat spot weld every couple of inches to position the piece, then alternate an inch of overlapping spot welds to keep the heat down, rather than draw a straight bead. the welds so far are too high, and the arc is still too aggressive. also getting a lot of wire sticking to the tip.

[James D. Clark]

I would try some .030 wire before giving up on it. That might help with the burn off and sticking to the tip.

[Planet X]

i've only had it a few days, so maybe some more time with it will produce better results on 20ga, but i'm not optimistic. it' just doesn't have a soft enough arc when turned down to the range that's suggested on the side panel for 20ga. (220 speed, 15V). i've adjusted it more and less, but still not happy. may have to get a 120V HH140 or something for the sheetmetal work. gas is C25, wire is .023, direction is right to left if that's what you mean, torch angled to the right a bit. for tack and spot 90°. butt welds on 20ga. i like to place a nice flat spot weld every couple of inches to position the piece, then alternate an inch of overlapping spot welds to keep the heat down, rather than draw a straight bead. the welds so far are too high, and the arc is still too aggressive. also getting a lot of wire sticking to the tip.

Guessing a typo "220 speed", but the chart on my machine shows for .025 wire speed of 120 with 15 Volts. Anyway no biggie. Don't really use the chart.

Well I am going to suggest a couple of things, but "aggressive arc" and " welds too high", those things are subjective so I can't help- would need to be there so you could show me .
But sheetmetal especially that thin is a tricky thing, and the small gun that comes with machines like the sp 135 & sp175 or the like are an advantage.Lighter and more manuverable.
I use a low energy mix for things this thin, in my case 97%argon w/ 3%Co2. But 98arg2oxy, or 95argon5Co2 could be substituted. So for example:
75Argon25Co2, settings 120 'speed' @ 15Volts now change to low engergy mix.
97argon3Co2, settings 120 'speed' @ 12-14volts. The lower voltage will aid with burn through.

I am assuming you changed the gun liner/contact tip/drive rolls, etc to match the .023 wire size. But some things that will contribute to burn back esp. with that tiny wire is too long of a stickout. Are you getting whiskers (lengths of wire sticking to part)?
Anyway adjusting the stickout does help control current (can lower/raise it), but there is a range up or down you can move the gun from part.
How big is the spool- you may need to use an adapter- now obviously it is feeding, but check the brake tension on the hub. If too tight and the spool is small (light) the wire will not feed enough length past the contact tip match the machines burnback time. What this means is the wire will overheat inside of the contact tip and just get out and melt-viola welded copper tip.

Unfortunetly the smallest wire I use is .030 (rarely at that), but it would be my first choice, but if YOU are getting burn through with the .024 it will only be worse with the larger wire.

Small occilations while welding will help flatten the weld and if you can move fast enough spread the heat away from the thin edge of the butt welds. If you are aiming your arc right at the gap where the two pieces meet- you are asking to melt through .

Anyway whats a lowly mig doing in a Porsche shop- thought that was tig only